System and method for transmitting bidirectional signals over a cable antenna

ABSTRACT

A method and system for data wireless systems on computers, for using the same cable to bi-directionally transmit antenna signals as well as other signals to and from the inside of a shielded computer housing. An example of a control signal is a connect signal for establishing initial contact between the computer and a remote wireless device. An example of a control signal transmitted from inside the computer housing to the outside, is a signal for lighting an LED. Antenna signals are separated from the control signals based on differences between these signals, for example, differences in frequency. In one embodiment, a capacitor filters out a DC control switch signal, while the high frequency antenna signal is filtered by the normal input pin circuitry of a processor.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application is a division of U.S. application Ser. No. 11/910,951,filed Aug. 3, 2004 entitled “System and Method for TransmittingBidirectional Signals Over a Cable Antenna,” which application isincorporated herein by reference.

STATEMENT AS TO RIGHTS TO INVENTIONS MADE UNDER FEDERALLY SPONSOREDRESEARCH OR DEVELOPMENT

Not Applicable

REFERENCE TO A “SEQUENCE LISTING,” A TABLE, OR A COMPUTER PROGRAMLISTING APPENDIX SUBMITTED ON A COMPACT DISK

Not Applicable

BACKGROUND OF THE INVENTION

The present invention relates generally to wireless communications, andmore specifically to bidirectional communication of control signals andantenna signals over a cable, through the housing of a computer.

Wireless technology has become increasingly popular in recent years.Many computer peripherals (e.g., keyboards, mice, trackballs, gamingdevices, speakers, etc.) are now wireless or cordless, and the conceptof the cordless desktop has risen in popularity. Various technologiesare used for wireless peripherals, such as technology utilizing 27 MHzfrequency, Bluetooth technology, and so on.

In addition, the concept of wireless Local Area Network (LAN) is alsoemerging. One technology that is being used for wireless LAN is inaccordance with the 802.11 standard (sometimes referred to as WirelessFidelity (Wi-Fi) technology).

In general, regardless of the specific purpose for which the wirelesstechnology is used, and regardless of the specific wireless technologyused, wireless communication employs signals that are transmitted from atransmitter to a receiver. (Often, there are transceivers on each end ofthe wireless communication path, so that each end can both receive andsend wireless signals.) The transmitter and receiver each have anantenna for transmission and reception of the wireless signals.

For purposes of further discussion, let us take the example of awireless keyboard in communication with a personal computer.Conventionally, a transceiver is connected to the computer externally.The antenna in the transceiver is thus also external to the computer'smetallic housing, and thus can communicate freely with the transceiverin the wireless keyboard. Having an external transceiver, however, canbe cumbersome, since the user has to plug in and manage another device.Thus, in accordance with embodiments of the present invention, thetransceiver connected to the computer is moved to within the metallichousing shielding the computer. The antenna of the transceiver, however,needs to be outside the metallic housing of the computer, in order forthe wireless signals to be unimpeded.

The transceiver located inside the computer housing thus needs to beconnected to an antenna module located outside the computer housing.This can be achieved by means of a cable which passes through thecomputer housing. In addition, apart from the antenna signals certainother signals also often need to be passed from outside the computerhousing to the transceiver, and from the transceiver to outside thecomputer housing. One example of such a signal is a “connect” signal toinitiate communication between the transceiver in the computer and thetransceiver in a wireless peripheral device. Another example of such asignal is when a user needs to be notified of certain events, and thenotification signal is initiated inside the computer housing, and needsto be perceptible to the user on the outside.

Generally separate cables and/or connections are used for transmittingthe antenna signals, and for transmitting the other signals. It is,however, desirable to reduce the number of cables used for severalreasons. First, cables can be expensive. Further, cables often usespecial connectors which add to the expense. Moreover, it is inelegantto have numerous or larger openings in the housing of the computer inorder to have numerous cables running through each of these openings.

Thus there is a need for a system and method for reducing the number ofcables transmitting signals from the inside of a computer housing to theoutside, and vice versa. Further, there is a need for a system andmethod for using the same cable for bi-directionally transmittingantenna signals as well as other signals from the inside of a computer'shousing to the outside.

BRIEF SUMMARY OF THE INVENTION

The present invention is a system and method for wireless systems fordata communications on computers, where cables can be used to transmitantenna signals as well as to bi-directionally communicate other signalsto and from the inside of a shielded computer housing. It is to be notedthat the present invention is not limited to computers, but rather toany device which has a housing, and which needs an external antenna.

In one embodiment, a system in accordance with the present invention canbe used for wireless computer peripherals (e.g., mice, keyboards, gamingdevices, speakers, etc.) using the 27 MHz wireless technology. Inanother embodiment, a system in accordance with the present inventioncan be used for wireless devices using the Bluetooth technology. In yetanother embodiment, a system in accordance with the present inventioncan be used with the Wi-Fi technology.

One or more antenna signals, as well as other signals, can becommunicated over the same cable from/to the inside of the shieldedcomputer housing. These other signals can include control signals, suchas signals for establishing initial contact between the computer and theremote wireless device, and signals for indicating the occurrence ofcertain pre-specified events on the computer. The former is an exampleof a signal which is transmitted from outside the computer housing tothe inside, while the latter is an example of a signal which istransmitted from inside the computer housing to the outside.

Since the same cable is used to transmit antenna signals and othersignals, these various signals need to be separated from each other. Ina system in accordance with one embodiment of the present invention,this separation is based on frequency differences between the antennasignals and the other signals. In one embodiment, various antennasignals can also be separated from each other based on frequencydifferences between them (e.g., Bluetooth signals and 27 MHz signals).In one embodiment, the signals are differentiated based on frequencyusing simple electrical components such as resistors and capacitors. Inone embodiment, a choke is also used for this purpose.

In one embodiment, the cable is shared between a control signal (e.g.,button press) that is a DC level, and a high frequency signal. A simplecircuit separates the DC from the high frequency signal. A capacitor canfilter out the DC from a receiver for the antenna signal, while the highfrequency antenna signal can be filtered from the input to a processorby the processor's internal input filtering and by taking advantage ofthe antenna signal being in the microvolt range, below the lowerdetection limit for the processor input pin.

The features and advantages described in this summary and the followingdetailed description are not all-inclusive, and particularly, manyadditional features and advantages will be apparent to one of ordinaryskill in the art in view of the drawings, specification, and claimshereof. Moreover, it should be noted that the language used in thespecification has been principally selected for readability andinstructional purposes, and may not have been selected to delineate orcircumscribe the inventive subject matter, resort to the claims beingnecessary to determine such inventive subject matter.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention has other advantages and features which will be morereadily apparent from the following detailed description of theinvention and the appended claims, when taken in conjunction with theaccompanying drawing, in which:

FIG. 1 is a system-level diagram of one embodiment of a data processingsystem having one or more cordless devices that includes an antennasystem in accordance with the present invention.

FIG. 2 is a block diagram of a wireless communication module whereseparate cables are used for transmission of antenna signals and othersignals.

FIG. 3 is a block diagram of a wireless communication module inaccordance with an embodiment of the present invention, where a singlecoaxial cable is used for transmission of antenna signals and othersignals.

FIG. 4 is a flowchart illustrating the functioning of a system inaccordance with an embodiment of the present invention.

FIG. 5 is a circuit diagram of an embodiment of the present invention inwhich the circuit can be used for transmitting antenna signals andcontrol signals over a single coaxial cable from the outside of acomputer housing to the inside.

FIG. 6 is a circuit diagram of an embodiment of the present invention inwhich the circuit can be used for bi-directional transmission of antennasignals and control signals over a single coaxial cable.

DETAILED DESCRIPTION OF THE INVENTION

The figures depict a preferred embodiment of the present invention forpurposes of illustration only. It is noted that similar or likereference numbers in the figures may indicate similar or likefunctionality. One of skill in the art will readily recognize from thefollowing discussion that alternative embodiments of the structures andmethods disclosed herein may be employed without departing from theprinciples of the invention(s) herein.

It is to be noted that a system in accordance with the present inventioncan be used in various different contexts. In particular, a system inaccordance with the present invention can be used in several contexts inwhich wireless technology is used for computers. In one embodiment, asystem in accordance with the present invention can be used for wirelesscomputer peripherals (e.g., mice, keyboards, gaming devices, speakers,etc.) using various types of wireless technologies. These can include,amongst other, 27 MHz wireless technology, Bluetooth technology. Inanother embodiment, a system in accordance with the present inventioncan be used with Wireless Local Area Network (WLAN) products. Forinstance, a system in accordance with an embodiment of the presentinvention can be used for wireless LAN products employing the 802.11technology (sometimes referred to as Wireless Fidelity (Wi-Fi)technology). For purposes of discussion, this application uses theexample of the use of the present invention in the context of wirelessperipheral devices.

FIG. 1 is a system-level diagram of one embodiment of a data processingsystem 100 having one or more cordless (or wireless) electronicperipheral devices. The data processing system 100 comprises a computer110, a transceiver 120 a, a monitor 130, and several wireless peripheraldevices 140-170.

The computer 110 may be a conventional intelligent device, for example,a personal computer, a personal digital assistant, a set-top box, or thelike. As mentioned above, in other embodiments, the present invention isused for any device which has a housing and requires an externalantenna. In one embodiment, the computer 110 includes a centralprocessing unit (CPU) 112, a memory 114, an optional storage device 116,an optional input/output port 118, and a wireless communication module121. The CPU 112, the memory 114, the storage device 116, theinput/output port 118, and the wireless communication module 121 arecoupled through a data bus 119.

In one embodiment the CPU 112 is a conventional processor, for example,an Intel (Santa Clara, Calif.) Pentium®-type processor or an IBMPowerPC™-type processor.

The memory 114 is a conventional memory, for example, a dynamic randomaccess memory or a static random access memory. The storage device 116is a conventional storage device, for example, a magnetic disk storagedevice, an optical disk storage device, a tape storage device, or asolid state (e.g., flash memory) storage device. The data bus 119 is aconventional data bus, for example, a system bus or a peripheralcomponent interconnect bus.

In addition, in accordance with an embodiment of the present invention,the wireless communication module 121 is partly within the housing ofthe computer 110, and partly outside of it. In particular, an antennamodule is outside the housing of the computer 110, while a transceiveris inside the housing of the computer 110, amongst other things. Thevarious components of the wireless communication module 121 aredescribed in more detail with respect to FIGS. 2 and 3.

Monitor 130 is any conventional display unit which can be used withcomputer 110. The peripheral devices may include control devices, forexample, a keyboard 140, a mouse 150. The peripheral devices may alsoinclude imaging devices, for example, a video camera 160 or a scanningdevice. Yet other peripheral devices include, for example, a gamingdevice 170 (e.g., a cordless driving wheel, joystick, or gamecontroller). Still other examples of peripheral devices are trackballs,touch pads, printers, entertainment devices (e.g., cordless speakers),digital pens, etc. Some or all of these peripheral devices arewireless/cordless, and are communicatively coupled wirelessly to thewireless communication module 121.

In one embodiment, a wireless peripheral device, such as the keyboard140, includes a MicroController Unit (or MCU) 142, and a transceiver 120a. It is noted that the memory may be incorporated within the MCU 142.In one embodiment, the transceiver 120 a is capable of both receivingand transmitting communication signals. It is to be noted that dependingon the specific wireless device, the transceiver 120 a may instead be areceiver which is capable of only receiving communication signals, or atransmitter which is capable of only transmitting communication signals.The transceiver 120 a is a conventional transceiver device. In addition,the peripheral device includes other components related to thefunctionality of the specific peripheral device. For instance, mouse 150may include an optical module, a memory, etc. In one embodiment, thevarious components of the wireless peripheral device are coupled throughan electrical signal line, which may be a type of data bus. In addition,it is to be noted that the various wireless devices also include a powersource to supply power to the appropriate components, for example, theMCU 142 or the transmitter 120 a.

The MCU 142 is a conventional MCU, for example a Motorola 6805 or 6808families of MCUs. The transceiver 120 a is a conventional transceiver.The components may be conventional components, for example, an opticalmodule assembly from Agilent Technologies (Palo Alto, Calif.).

As mentioned above, the computer 110 and the peripheral device, e.g.,the keyboard 140, are communicatively coupled through the transceiver120 a and the wireless communication module 121. For example, thekeyboard 140 sends data to the computer 110 using any wireless protocol.More particularly, the transceiver 120 a couples with an antenna systemthrough which the wireless protocol is sent via a communication signalto an antenna that couples with a transceiver 120 a in the wirelesscommunication module 121 at the computer 110. In one embodiment, thecommunication signal may be a radio frequency signal operating in a widerange of frequencies, for example, from a few Mega Hertz to several GigaHertz. In one embodiment, the communication signal may be a Bluetoothsignal, whose frequency is in several Giga Hertz (e.g., 2.4 GHz).

Referring again to wireless communication module 121, it can be seenthat part of the wireless communication module 121 is located within thehousing of the computer 110, while part of the wireless communicationmodule 121 is located outside the housing of the computer 110. This isbecause the computer housing is metallically shielded, and at least theantenna module of the wireless communication module 121 needs to beoutside this metallic shield in order to function adequately.

In order to connect the antenna module (which is placed outside thecomputer housing) with the remainder of the transceiver modules (whichare placed inside the computer), in one embodiment, a coaxial cable isused. Other signals which need to be transmitted are sent over anothercable connecting the inside and the outside of the computer housing.This is illustrated in FIG. 2.

FIG. 2 is a block diagram of one embodiment of a wireless communicationmodule 121, where separate cables are required for transmitting antennasignals and control signals across the computer's metallically shieldedhousing. The wireless communication module 121 is comprised of anantenna module 210, an impedance matching module 220, a coaxial cable230 a, a transceiver 120 b, a signal receiving and/or generating module240, a second cable 230 b, and a Micro Controller Unit (MCU) 113.

The antenna module 210 can include any antenna which can be used forwireless communications. Examples of antennas include loop antennas,whip antennas, etc. The specific antenna used will depend on thetechnology used for wireless communication. For instance, antennas usetechnologies including radio-frequency wireless technology, Bluetooth,etc.

Coaxial cable 230 a is a type of wire that consists of a center wiresurrounded by insulation and then a grounded shield of braided wire. Theshield minimizes electrical and radio frequency interference. Coaxialcables are generally more expensive than standard cables, but are muchless susceptible to interference, emit less interference and can carrymuch more data. It is to be noted that other types of cables could beused in place of coaxial cable 230 a, and that the use of the coaxialcable is one possible embodiment.

The coaxial cable 230 a generally has impedance different from theimpedance of the antenna module 210. In one embodiment, the coaxialcable has low impedance (for example, 50 ohms), while the impedance ofthe antenna module 210 is high. Thus, an impedance matching module 220is needed in order to match the different impedances of the coaxialcable 230 a and the antenna module 210. The impedance matching module220 can be any type of passive transformer used in the art.

The coaxial cable 230 a communicatively couples the antenna module 210,which is located outside the housing of the computer 110, to thetransceiver 120 b, which is located inside the housing of the computer110. The transceiver 120 b can be any conventional transceiver which canboth transmit and receive signals. In one embodiment, only a receiver isused, while in another embodiment, only a transmitter is used. Thetransceiver 120 b communicates with transceiver(s) 120 a in the wirelessperipheral devices.

In addition to antenna signal, it is often desirable to communicateother signals to and from inside of the computer housing to the outsideof the computer housing. One example is a control signal which can betriggered by a user by using a switch on transceiver 120 b. Such aswitch needs to be accessed by a user on the outside of the computerhousing. Such a switch can be used to transmit signals to thetransceiver, which in accordance with an embodiment of the presentinvention, is located inside the housing of the computer. For instance,wireless peripheral devices often have a “connect” button in order toestablish the initial connection between the transceiver 120 a in thewireless peripheral device and the transceiver 120 b connected to thecomputer. A corresponding “connect” button exists on transceiver 120 b.When both “connect” buttons are pressed, a communication link isestablished between the two transceivers 120 a & 120 b.

It may also be desirable to send signals from within the computerhousing to the outside. For instance, a user may want to receive anindication of the occurrence of certain events, by means of seeing anLED light up when these events occur. Examples of such events includeestablishing and/or losing of the connection, a signal being sent, etc.

Yet another example of signals which may be transmitted from/to theinside of the computer housing includes a series of control signalswhich controls numerous buttons/LEDs. In such an embodiment, someintelligence is present near the antenna module to distinguish betweenthe various signals. This intelligence needs some power to operate, andin one embodiment, power is also sent over the same cable whichtransmits the antenna signals and the control signals.

It is to be noted that various different antenna signals may also besent/received from the inside of the computer housing to the outside.For instance, a Bluetooth antenna signal and a 27 MHz antenna signal mayboth be sent/received.

One solution for transmitting these other signals from and to the insideof the metal housing, is to use a separate cable 230 b to transmit suchsignals, as shown in FIG. 2. The cable 230 b communicatively couples thesignal receiving and/or generating module 240 with the transceiver 120b.

The solution illustrated in FIG. 2 however includes multiple cables 230a and 230 b. It is desirable to reduce the number of cables used forseveral reasons. First, cables are expensive. Further, cables often usespecial connectors, which add to the expense. Moreover, it is inelegantto have numerous or larger openings in the housing of the computer inorder to have several cables running through each of these openings.

In accordance with an embodiment of the present invention, the samecable can be used for transmitting various antenna signals, as well ascommunicating other signals bi-directionally between the inside of thecomputer housing and the outside. In one embodiment, the same cable isalso used to transmit power between the inside of the computer housingand the outside. It is to be noted that some specific embodimentsdiscussed below focus on separating an antenna signal from a controlsignal. However, the techniques discussed below have more generalapplicability, and can be used for various other purposes, such asseparating power from antenna signals, separating various antennasignals from each other, etc.

FIG. 3 is a block diagram of a system 300 in accordance with oneembodiment of the present invention, where a single cable can be used totransmit not only antenna signals, but also to communicate controlsignals across the computer's metallic shield housing. System 300comprises an antenna module 210, an impedance matching module 220, asignal receiving and/or generating modules 240, a coaxial cable 230,signal separator modules 340 a and 340 b, a transceiver 120 b, and anMCU 113.

The antenna module 210, the impedance matching module 220, a signalreceiving and/or generating module 240, the transceiver 120 a, and theMCU 113, have been described above with respect to FIG. 2.

The coaxial cable 230 is used, in this embodiment, to transmit bothantenna signals as well as other signals (e.g., control signals)bi-directionally. It is to be noted that in other embodiments, othertypes of cables are used in place of coaxial cable 230. Since the samecable 230 is used to transmit different types of signals, signalseparator modules 340 a and 340 b are needed to separate out the antennasignal from other non-antenna signals.

In accordance with an embodiment of the present invention, these othersignals are distinguishable in some way from the antenna signals. Forinstance, while antenna signals are relatively high frequency signals(generally in several Mega-Hertz at the least), low frequency signals(e.g., only a few hundreds of Hertz to a few kilo-Hertz) could be usedto transmit other information. Thus in one embodiment, the signalseparator modules 340 a and 340 b use frequency filters to distinguishantenna signals from these various signals.

For incoming signals, once the other signals are separated from theantenna signals, they can be directed to their respective destinations,where they can be processed. In one embodiment, antenna signals aredirected to the transceiver 120 a, while the other signals are directedto the MCU 113.

FIG. 4 is a flowchart illustrating the functioning of a system inaccordance with an embodiment of the present invention. The antennamodule 210 communicates (step 410), via antenna signals, with a remotewireless device. In one embodiment, the antenna module receives antennasignals from the remote wireless device. In another embodiment, theantenna module 210 sends antenna signals to the remote wireless device.In yet another embodiment, the antenna module 210 sends as well asreceives antenna signals from the remote wireless device.

For purposes of discussion, let us focus on the embodiment where antennasignals are received by the antenna module 210 from the remote wirelessdevice, and where a control signal is to be transmitted from outside thecomputer housing to the inside. The antenna signals, as well as any thecontrol signals, are transmitted (step 420) from the outside of thecomputer housing to the inside over the coaxial cable 230.

These signals are then separated (step 430) on the inside of thecomputer housing. The antenna signals are then routed (step 440) to thetransceiver 120 b, while the control signals are routed (Step 440) tothe MCU 113, for further processing.

It will be obvious to one of skill in the art that a system inaccordance with an embodiment of the present invention is also usable ina situation where control signals as well as antenna signals aretransmitted from the inside of the computer housing to the outside.Moreover, a system in accordance with an embodiment of the presentinvention also accommodates a situation where the control signal istransmitted in one direction (e.g., from the inside of the computerhousing to the outside) and the antenna signal is transmitted in theother (e.g., from the outside of the computer housing to the inside).Thus a system in accordance with an embodiment of the present inventionis a bi-directional system for both the antenna signals as well as theother signals.

FIG. 5 is a circuit diagram representing one possible embodiment 500 inwhich a control signal can be transmitted by the user to the MCU 113located within the metal covering of the CPU. As mentioned above, thecoaxial cable 230 connects the inside of the CPU's housing with theoutside. In FIG. 5, the portion to the right of the coaxial cable 230represents the inside of the computer housing, and the portion to theleft of the coaxial cable 230 represents the outside.

As discussed above, the antenna module 210 and the impedance matchingmodule 220 are located outside the computer's shielded housing. In FIG.5, the antenna 510 is connected to pins P3 and P5 of the impedancematching module 220. Two other pins, P2 and P6, of the impedancematching module 220 are connected to a resistor R1, and to ground,respectively. Resistance R1 is connected to ground through a switch 520.This switch. 520 is the “button” that the user can manipulate totransmit signals from outside the computer housing to the MCU 113 on theinside.

The coaxial cable 230 has three connections on the inside of thecomputer housing. One connection is to an “in” pin in the MCU 113, aswell as to one end of a resistor R2. The other end of the resistor R2 isconnected to high voltage Vcc (e.g., 5V or 3.3. V). Relative toresistance R2, resistance R1 is small. For example, in one embodiment,resistance R2 is 100 kilo-ohms, and resistance R1 is 10 kilo-ohms.

The second connection from the coaxial cable 230 is to an “RFin” pin P1in the transceiver 120 b, via a capacitor C1. In one embodiment, thecapacitor used is 100 nano-Farads. The third connection from the cable230 is to ground. An “RFgnd” pin P2 in the transceiver 120 a is alsoconnected to ground.

The functioning of circuit 500 is as follows. When the switch 520 is notpressed by the user, no current can flow through resistor R1. Thus, withswitch 520 open, only antenna signals are being communicated fromoutside the computer housing to the inside. Antenna signals are highfrequency signals (when compared to the low frequency control signals).Capacitor C1 serves as a short circuit (or as very low impedance) forhigh frequency signals, and allows them to pass through. Thus the highfrequency antenna signals will be transmitted to the transceiver 120 b,via pin “RFin”.

When the switch 520 is closed, current flows through resistor R1. A lowfrequency signal is transmitted from outside the computer housing to theinside. Direct Current (DC) signals are blocked, and low frequencysignals are attenuated, by the capacitor C1. This fact is used to directthe low frequency control signals to the MCU 113, and not to thetransceiver 120 b. When switch 520 is closed, resistors R2 and R1 areconnected in a voltage divider configuration. The working of the voltagedivider will be governed by the ratio of R2:R1, which is 10:1 in thisembodiment. Thus, in this embodiment, the “in” pin on the MCU 113 is ata low voltage of 0.1 Vcc when the switch 520 is closed. On the otherhand, when the switch 520 is open, the “in” pin on the MCU 113 is pulledto a high voltage of Vcc. Thus the “in” pin of the MCU 113 can detectwhether the switch 520 is open or closed based on whether it is at a lowor a high voltage. R2's role when switch is open is to pull up the MCUinput to a high level. The value of R2 is much higher than cableimpedance because the high value makes sure that R2 does not change(does not impact) the antenna system impedance.

As discussed above, because capacitor C1 provides low impedance to highfrequency signals, it allows the high frequency antenna signals to passthrough, while it attenuates/blocks the much lower frequency controlsignals. Thus the low frequency control signal is received by the MCU113 at the “in” pin, but not by the “RFin” pin of the transceiver 120 b.The microprocessor input pin does not pick up the high frequency antennasignal due to internal filtering connected to the input pin, and alsobecause the radio frequency signal voltage level is very small(microvolts) compared to the switch (DC) signal (Volts). Thus circuit500 illustrates a system in accordance with an embodiment of the presentinvention, in which control signals can be transmitted from the outsideof the computer housing to the inside, over the same cable on whichantenna signals are transmitted.

FIG. 6 is a circuit diagram 600 illustrating bi-directional transmissionof control signals using the same cable over which antenna signals aretransmitted, in accordance with one embodiment of the present invention.For example, a button could be pressed by a user on the outside totransmit a signal to the inside of the computer housing. In addition,the occurrence of some events could trigger the transmission of a signalfrom the inside of the housing, resulting in the lighting up of a LightEmitting Diode (LED) on the outside, as a notification to the user.

Circuit 600 also includes an antenna 510 and an impedance matchingmodule 220. Circuit 600 is first described, and then its functionalityis explained.

Four pins, P3, P5, P2 and P6, in the impedance matching module 220 areshown. Pins P3 and P5 are connected to the antenna 510. Pin P6 isconnected to ground. Pin P2 is connected to one end of a choke 620. Theother end of the choke 620 is connected to one end of an LED 630. LED630 can light up to notify the user of some predetermined event. Theother end of the LED 630 is connected to resistor R1. In one embodiment,resistor R1 can be 200 ohms. The other end of R1 is connected to aswitch 640 which can be manipulated to transmit signals to within thecomputer housing.

The connection between pin P1 of the impedance matching module and thechoke 620 is also connected to one end of the coaxial cable 230. Inaddition, ground is also connected to one end of the coaxial cable 230.

Inside the computer housing, a power source Vcc (e.g., 5V or 3.3 V) isconnected to the collector of a PNP transistor 650. The collector of thetransistor 650 is connected to ground through resistor R4. In oneembodiment, the resistor R4 is 100 kilo-ohms. The base of the transistor650 is connected to an “out” pin in the MCU 113, via resistors R2 andR3. In one embodiment, resistor R2 is 100 kilo-ohms, and resistor R3 is100 ohms. The base of the transistor 650 is also connected, via R2alone, to one end of the coaxial cable 230. This end of the coaxialcable 230 is also connected, via a capacitor C1, to an “RFin” pin of thetransceiver 120 a. In one embodiment, a 100 nano-Farads capacitor isused. The transceiver 120 a also has a pin “RFgnd” which is connected toground, as well as to the coaxial cable 230. Further, the MCU 113 has an“in” pin which is connected to ground via resistor R4.

Let us now discuss how circuit 600 functions. First, let us discuss thetransmission of signals from within the computer housing to the outside.In order for this to happen, the switch 640 should be closed in thecurrent embodiment.

When the switch 640 is closed, a current passes through the choke 620,the LED 630, and the resistor R1 which are in series. The choke 620allows only DC or low frequency signals to pass through, whileblocking/attenuating high frequency signals. When the MCU 113 “out” pinis set to high, (e.g., Vcc), the DC signal from the high “out” pin ofthe MCU 113 will be communicated, via R3 and the cable 230, to the choke620. The choke 620, in turn, will allow this signal to pass throughitself, the LED 630, resistor R1, and the switch 640. Thus, when the MCU113 “out” pin is set to high, (e.g., Vcc), the LED 630 is lit. (Anyantenna signal on the “RFin” pin of the transceiver 120 a does notaffect the LED 630 in any way, because the choke 620 will not allowthese high frequency AC signals to pass through.)

In contrast, when the MCU 113 “out” pin is set to low (e.g., ground),the LED 630 is not lit. This is because in such a situation, there is novoltage difference between one end and the other of the seriescombination of the choke 620, the LED 630, the resistor R1, and theswitch 640. Thus no signal passes through the LED 630, and it remainsunlit when the “out” pin of the MCU 113 is set to low. (Once again, anyantenna signal on the “RFin” pin of the transceiver 120 a does notaffect the LED 630 in any way, because the choke 620 will not allowthese high frequency AC signals to pass through.) Thus signals can betransmitted from within the computer housing to the outside bymanipulating MCU “out”, and the user notification can occur via LED 630.

Now let us discuss transmitting signals from outside the housing to theinside of the housing. In order to transmit such signals, in thisembodiment, the “out” pin of the MCU 113 is set to high, and the switch640 is manipulated.

The transistor 650 can determine whether the switch 640 is closed oropen, because, in this embodiment, a current flows through thetransistor 650 only when the switch 640 is closed. When a current flowsthrough the transistor 650 (i.e. when the switch 640 is closed), the“in” pin of the MCU 113 will have a high voltage. If the switch 640 isopen, no current flows through transistor 650, and the “in” pin of theMCU 113 will be low. Thus, by detecting the voltage at the “in” pin ofthe MCU 113, it can be determined whether the switch 640 is open orclosed. As mentioned above, because the choke 620 does not allow highfrequency signals to pass through, the LED 630 and the switch 640 areunaffected by any antenna signals. In this figure, there are basicallytwo functions:

1) Assuming the switch is closed (the majority of cases). Through theMCU out pin, one can control the LED on/off.2) Assuming MCU out is High-Z. The MCU In pin can get the status of theswitch.

As will be understood by those of skill in the art, the presentinvention may be embodied in other specific forms without departing fromthe essential characteristics thereof. For example, embodiments of thepresent invention could also be used with wireless communications usingsome types of infra-red technology. As another example, the LED andswitch in FIGS. 5 and/or 6 could be replaced by other components such asMCUs. As yet another example, various antenna signals using differentfrequencies can be multiplexed for transmission over the same cable, andthen de-multiplexed based on their different frequencies. In anotheralternate embodiment, the LED is in parallel with the switch, and theswitch can be opened to allow LED control by the MCU. While particularembodiments and applications of the present invention have beenillustrated and described, it is to be understood that the invention isnot limited to the precise construction and components disclosed hereinand that various modifications, changes, and variations which will beapparent to those skilled in the art may be made in the arrangement,operation and details of the method and apparatus of the presentinvention disclosed herein, without departing from the spirit and scopeof the invention, which is defined in the following claims.

1. A method for transmitting a plurality of signals over a cable fromthe inside of a shielded housing of a device to the outside of thehousing, and routing the plurality of signals appropriately, wherein oneof the plurality of signals is an antenna signal for wirelesscommunication, the method comprising: transmitting the plurality ofsignals over the cable from the inside of a shielded housing of a deviceto the outside of the housing; separating the plurality of signals intoan antenna signal and a second of the plurality of signals; routing theantenna signal to an antenna for communication with a remotetransceiver; and routing the second of the plurality of signals to asignal receiving module.
 2. The method of claim 1, wherein the antennasignal has a first frequency and the second of the plurality of signalshas a second frequency.
 3. The method of claim 2, wherein the secondfrequency is lower than the first frequency.
 4. The method of claim 2,wherein the steps of separating the plurality of signals comprise:selectively allowing the first frequency to pass through whileselectively blocking the second frequency along a first path to theantenna; and selectively allowing the second frequency to pass throughwhile selectively blocking the first frequency along a second path tothe signal receiving module.
 5. The method of claim 1, wherein thesignal receiving module is a Light Emitting Diode.
 6. The method ofclaim 1, wherein the step of separating the plurality of signals furthercomprises separating the plurality of signals into a third of theplurality of signals.
 7. The method of claim 6, wherein the third of theplurality of signals is a second antenna signal.
 8. The method of claim6, wherein the second of the plurality of signals is a control signal.9. The method of claim 1, wherein the second of the plurality of signalsis a control signal.
 10. A computing device having an electromagneticshielded housing, comprising: an antenna module outside said housing forreceiving wireless communications and generating an antenna signal; acontrol switch for generating a DC control signal; a cable, coupled tothe both the antenna module and the control switch, for transmittingboth the DC control signal and the antenna signal to the inside of thehousing; an antenna signal receiver; a capacitor connected between thecable and said antenna signal receiver to filter out said DC controlsignal; a Micro Controller Unit (MCU) having an input coupled to thecable for receiving the DC control signal, said input being connected tofiltering circuitry inside said MCU for filtering said antenna signal.11. The computing device of claim 10 wherein said filtering signalfilters based on amplitude, with said antenna signal having a voltagebelow an input detection level of said MCU input.
 12. The computingdevice of claim 10 further comprising: a light emitting diode (LED) inseries with said control switch; a circuit, coupled to said cable, saidMCU input and an output of said MCU, said circuit being configured toallow said MCU to read said DC control signal through said input, and toactivate said LED through said output.